App experience drives healthy mobile ecosystems. However, mobile platforms
present unique challenges to developers seeking to provide such experiences:
device heterogeneity, wireless network diversity, and unpredictable sensor
inputs. We propose Contextual Fuzzer, a cloud-based testing service that
addresses two challenges. First, it provides a large set of realistic mobile
contextual parameters to developers with emulators. Second, it enables scalable
mobile context exploration with app similarity networks. To evaluate the system
design, we profile 147 Windows Store mobile apps on our testbed. Results show
that we can uncover up to 11 times more crashes than existing testing tools
without mobile context. In addition, our app similarity network increases the
number of abnormal performances found in a given time by up to 36{\%}, as compared
to the current practices.